Superconductivity of Hg_(1−x)Ag_xBa_1.9La_0.1CuO_y (0≤x≤0.6) Materials

Abstract

Hg_(1−x)Ag_xBa_1.9La_0.1CuO_y materials are prepared directly from the oxide powders. Substitution of 5 at.% La³⁺ for Ba²⁺ chemically stabilize the materials. Ag substitution for Hg increases the Superconducting volume and enhances the Superconducting grain size. The Lattice parameters of the Superconducting tetragonal phase do not change but T_c decreases with increasing Ag-concentration from 92.5 (x = 0) to 78 K (x = 0.6). Maximum intra-grain critical current density estimated from the magnetization data is 1.4 × 10⁶ A/cm² (70 K, H = 0) for the composition Hg_0.8Ag_0.2Ba_1.9La_0.1CuO_y. Ag substitution for Hg transforms the semiconducting HgBa_1.9La_0.1CuO_y to metallic state and the electrical resistivity of the materials decreases with increasing Ag-concentration. Inter-grain critical current density increases with Ag-concentration and a maximum value of 25A/cm² (77 K; H = 0) is observed. This indicates that the presence of Ag provides extra pinning centers in the grains or at the grain boundaries and enhances the inter-grain electrical conductivity.